Subjective-Objective Sleep Discrepancy in Schizophrenia

Subjective methods are often employed for sleep assessment due to their ease of use, but the results may not concur with objective findings. This discrepancy may be present in schizophrenia; however, limited data are available. We performed a secondary analysis to evaluate the agreement between 1-week actigraphy and sleep diary-derived parameters and factors that contribute to subjective-objective sleep discrepancy.

66 outpatients with schizophrenia (mean age = 44.08 years; 45.45% males).

Agreement between subjective-objective parameters was assessed using two-way repeated measures ANOVA, Pearson's correlation, and Bland-Altman plot. The magnitude of discrepancy was quantified using Cohen's d. Pearson's correlation was used to determine the significant factors of subjective-objective sleep discrepancy. Benjamini-Hochberg adjustment was performed to account for multiple testing.

On average, sleep diaries overestimated sleep onset latency by 20.45 min, total sleep time by 37.63 min, and sleep efficiency by 4.29%, but underestimated wake after sleep onset by 33.28 min. Cohen's d ranged between 0.61 and 1.41. Subjective-objective discrepancies were significantly associated with marital and employment status, self-reported sleep disturbance, delayed sleep-wake phase disorder, chronotype, and psychosocial functioning (r = 0.32-0.44; Benjamini-Hochberg corrected p < .05).

Our findings show that differences between subjective and objective measurements of sleep are present in schizophrenia. Although actigraphy is not a standard procedure for sleep disturbance in schizophrenia, clinical judgment should be used if patients are suspected to have overestimated their sleep difficulties. Further studies should examine whether feedback based on actigraphy can benefit patients with schizophrenia and comorbid sleep disturbances.